HP Large-Bore

[Lockednloaded]

This is a gun I threw together out of mainly spare part. Its main purpose was to entertain and to awe, and I think it fits the bill. I didn't want to fiddle with a homemade valve on this project. I wanted reliable, simple, and relatively powerful, so I used a 3/4" QEV piloted by a 1/4" QEV and a 1/8" slide valve. Slide valves are notorious for being the most awkward DCVs, so I added a trigger and a spring return to make it more ergonomic.

Specifications
Firing Valve -> 3/4" QEV
Pilot Valve -> 1/4" QEV+1/8" slide valve
Barrels -> any thing from 1" up to 2"
Chamber -> An old FE probably has the same volume a 3" PVC chamber of equal length.
Firing Pressure -> 40-300psi (the highest I've taken it is 200 for now)

I think that should cover everything, so here's some pictures:

The full cannon with the short 2" barrel, I couldn't fit any of the longer barrels into the frame but I guess I could fit my toe...:


Valve area with custom schrader cap (Its a bolt):


FE connection made with a standard SCH 80 PVC nipple, sorry its blurry:


A little bit of damage:

Two boards just minding their own business:




And then after a "lime shot" at only 100psi from 10m:




Thanks for reading this far , I hope you liked it. Please voice any concerns or comments you may have.

~LnL

[Gun Freak]

Sick. I like the chamber too. It's the same FE I have What have you tested that tank to? I've done so to 200 psi for about 45 minutes. Your valves are nice too. Looks nice and compact, I like it.

[Lockednloaded]

tested the FE to 300, pumped it up to 200 with my bike pump, then over the course of a day I topped it off to 300...with a shock pump

[Gun Freak]

LOL I bet your arm was sore hahahahahha. Thats good to hear, I usually pump 160 to 180 in mine with my 3 stage pump. It held over 140 psi for 12 hours only losing about 9 psi I was happy.

[Lockednloaded]

I forgot to include this in the post, but I've made a really simple, super effective mortar shell for this. Basically, it is a spray paint cap with for cuts down the sides. It is a tight fit in the barrel and you just fill it with BBs, PBs, Acorns, etc.. then push it down the barrel. After that, you put a balled up paper towel down the barrel so the payload doesn't fall out.

When shot upwards at 60psi, the shell spun, and kept all the BBs in. But when it reached its max hight, it split open and drifted to earth, releasing a BB shower over a small area.

[lozz08]

Now THAT is cool. The gun is just a QEV gun but your mortar idea could have awesome implications for an airsoft or paintball game. The gun is very well built too.

[Lockednloaded]

thanks lozz08, an airsoft mortar isn't new, but having a safe shell makes the spreads much tighter. I shot one straight up toda and stood under the rain of BBs, each one was comparable to a cheap mini-electric airsoft gun

[Lockednloaded]

sorry to double post, but I've got some paint questions:

Would krylon fusion bond well to my metal fittings and valves? I don't think I've seen many painted metal fittings.

And to paint the FE, do I have to strip the current coat, and if I did, would it weaken the tank?

[Technician1002]

If the tank is powder coated, the coating is a type of plastic. A light sanding and Fusion should work well. As for the metal parts, use white primer first, then paint it. Follow the directions and be absolutely sure no oil remains from cutting the threads. A tiny bit of oil will messs up an otherwise good paint job.

[Lockednloaded]

Thanks tech, I'll do that once I get a color scheme worked out

Also, another question:
Which would offer more power: my current setup, or a 3/8" slide valve directly piloting to 3/4" QEV

[Gun Freak]

Also, another question:
Which would offer more power: my current setup, or a 3/8" slide valve directly piloting to 3/4" QEV

I think a 1/4" QEV is better than a 3/8 slide valve.

[Technician1002]

In regards to raw power, using a valve and plumbing between the chamber and barrel that is at least 2/3rds the diameter of the barrel is the single largest improvement I can think of, but that would be a major rebuild.

Using a golf ball barrel, my 2 inch valve at 50 PSI outperforms my 1 inch valve at 100 PSI in range.

With a 2 inch barrel, try to use at least a 1.5 inch valve and plumbing. 3/4 inch is hurting your potential.

[Lockednloaded]

Thats certainly an option to get some raw power out of this, but That would require large, not to mention heavy and pricey, galvanized parts.

[Lockednloaded]

sorry to bump this, but I just need to know one thing:
How much pressure could this particular QEV hold? ignore the current chamber setup, I'm just asking about the valve

[jackssmirkingrevenge]

What's the shear stength of those bolts

I'd be more concerned about the diaphragm at higher pressures that the casing.